This invention relates generally to the field of orthopedic medicine and more specifically to a custom-moldable wrist splint and a method for using such a splint to relieve and treat the symptoms of carpal tunnel syndrome.
Carpal tunnel syndrome occurs as a result of chronic irritation to the median nerve. The median nerve and the tendons that connect the muscles of the forearm to the fingers of the hand pass through the carpal tunnel. The carpal tunnel is a passageway defined by the eight carpal bones of the wrist and the transverse carpal ligament, which interconnects the hook of the hamate and the tubercle of the trapezium. Carpal tunnel syndrome results when the median nerve becomes constricted within the carpal tunnel, usually by the swelling of the tendons. Such constriction pushes the median nerve against the transverse carpal ligament located directly above the nerve.
The median nerve relays sensation from the palm of the hand and fingers. Continuous constriction of the median nerve causes it to gradually deteriorate, which in turn causes numbness, tingling and pain in the fingers and hand. Occasionally, such constriction also produces pain and parasthesia in the arm and shoulder. If left untreated, carpal tunnel syndrome can ultimately cause the muscles on the affected hand to weaken and atrophy.
Causes of carpal tunnel syndrome are controversial. However, the syndrome has been attributed to those repetitive uses of the hand and wrist that require forceful movements in which the wrist is extended. Such uses include, but are not limited to, using a keyboard or a screwdriver. Pregnant women and persons with diabetes or hypothyroidism are at an increased risk of developing carpal tunnel syndrome.
Severe cases of carpal tunnel syndrome are often treated by injecting corticosteroids into the affected nerve. The syndrome is also treated using a surgical procedure known as a xe2x80x9ccarpal tunnel releasexe2x80x9d in which the bands of tendons placing pressure on the median nerve are released. Although severe cases of carpal tunnel syndrome may require pharmaceutical or surgical intervention, the vast majority of cases may be resolved using much simpler methods, especially when treatment is initiated at the onset of symptoms. One form of early treatment is to splint the hand and wrist to provide support to the muscles of the hand and wrist. This treatment, combined with rest and correction or elimination of the suspected environmental factors contributing to the symptoms (for example, repositioning or changing a computer keyboard), can often avoid the need for injections or surgery.
Prior art splints often include a soft component to place near the skin and a hard, shell-like outer cover. The soft component is intended not only to cushion against the injured anatomy, but also to accommodate itself to the varying configurations of differing sized and shaped anatomy of patients. Other splints are glove-like in design and are provided with bendable plastic or metal stays that are bent to maintain the hand and wrist in a desired position.
Some prior art splints are constructed of or include thermosetting materials. Such materials are first heated and then formed to the hand and wrist while the materials are still warm. Splints formed from thermosetting materials cannot be used without a heat source, and the splints are susceptible to over-or-underheating. In addition, body heat can soften or at least increase the flexibility of the splint, which decreases the effectiveness of the protection offered by the splint.
The present invention overcomes the disadvantages of prior art splints by providing a splint that can be applied to the hand and wrist in such a way as to achieve a true custom fit from a universal design. The invention utilizes a moisture-curable resin which results in a very rigid splint that holds the shape into which it has been molded. No heat is required. A source of water is the only additional material necessary to harden the splint. Atmospheric moisture alone will cure the splint into its hardened position in a relatively short period of time; however, the resin in or on the splint will typically be activated by immersing the splint in water.
The splint is inexpensive, easy to fabricate, easy to fit and comfortable to wear. Since the splint has a single shape and size, hospitals, clinics, emergency care facilities and other health care providers can easily and inexpensively maintain a necessary inventory of splints.
In contrast to those prior art splints which are applied only to the dorsal aspect of the wrist, the splints of the present invention are utilized in pairs. Two of the splints are custom-fitted to the affected hand and wristxe2x80x94one on the dorsal aspect and one on the volar aspect thereofxe2x80x94to achieve a true four-point fixation of the injury. Unlike other splints which are utilized in pairs, the splints of the present invention feature a unique shape that accommodates and enables movement of the thumb and associated carpometacarpal joint while simultaneously providing enhanced support to the heads of the second through fourth metacarpals and metacarpophalangeal joints associated therewith. This provides greater support to the injured area and reduces the extent of residual movement of the hand and wrist.
Therefore, it is an object of the invention to provide a wrist splint assembly having two splints that are interchangeable between left and right hands.
It is another object of the invention to provide a wrist splint assembly that can be easily placed on and removed from the hand and wrist by the patient.
It is another object of the invention to provide a wrist splint assembly including a wrist splint that is interchangeable between the volar aspect of one hand to the dorsal aspect of the other hand prior to being hardened into a custom-fitted shape.
It is another object of the invention to provide a wrist splint assembly that allows enhanced mobility of the thumb and associated carpometacarpal joint while simultaneously providing increased support of the heads of the second through fourth metacarpals and carpometaphalangeal joints associated therewith.
It is another object of the invention to provide a wrist splint that is stored in a secondary, cure-retarding inner package, which is in turn sealed within an outer moisture-proof pouch, until the splint is ready for being applied to the body part to be protected.
It is another object of the invention to provide a wrist splint assembly that includes two or more splints sealed within a single moisture-impervious package for ease of removal and use.
It is another object of the invention to provide a wrist splint that hardens in the presence of moisture to form a very lightweight, protective splint.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a wrist splint assembly for being custom-fitted to a hand and wrist to be supported. The wrist splint assembly includes a first splint for being positioned against and formed to the volar aspect of the hand and wrist, and a second splint for being positioned against and formed to the dorsal aspect of the hand and wrist. Each of the first and second splints defines a concave side edge extending inwardly toward the longitudinal axis of the splint for permitting ease of movement of the thumb and associated carpometacarpal joint of the hand against which the splint is positioned. Each of the first and second splints also includes an inner cushion layer for being placed on and conformed to the shape of the hand and wrist, and an initially flexible intermediate layer overlying the inner cushion. The intermediate layer is a substrate impregnated with a moisture-curable resin that hardens upon curing to form a rigid structure of the substrate that retains a shape into which it is molded during curing for maintaining the flexible inner cushion layer in a conforming shape against the hand and wrist. Each of the first and second splints also includes a flexible outer layer overlying the intermediate layer and attached to the inner cushion layer for enclosing the intermediate layer for forming the inner layer, intermediate layer and outer layer into a single, integrated splint structure. The wrist splint assembly also includes a support for retaining the first and second splints in position on the hand and wrist during use of the splint assembly.
According to one preferred embodiment of the invention, the support is an elongate strap having an outer surface and first and second ends. The first end of the strap is releasably attached to a complementary fastener attached to a preselected one of the outer layers of the first and second splints. The second end of the strap is releasably attached to the outer surface of the strap, thereby permitting the strap to encircle the wrist for securing the first and second splints against the hand and wrist.
According to another preferred embodiment of the invention, the support also includes a second elongate strap having an outer surface and first and second ends. The first end of the second strap is releasably attached to a complementary second fastener attached to a preselected one of the outer layers of the first and second splints. The second end of the second strap is releasably attached to the outer surface of the second strap, thereby permitting the second strap to encircle the wrist for securing the first and second splints against the hand and wrist.
According to yet another preferred embodiment of the invention, the support also a third elongate strap having an outer surface and first and second ends. The first end of the third strap is releasably attached to a complementary third fastener attached to a preselected one of the outer layers of the first and second splints. The second end of the third strap is releasably attached to the outer surface of the third strap, thereby permitting the third strap to encircle the hand for securing the first and second splints against the hand and wrist.
According to yet another preferred embodiment of the invention, the fastener, second fastener, and third fastener are patches of hooked material.
According to yet another preferred embodiment of the invention, the outer surface of the strap, second strap and third strap are formed from looped material.
According to yet another preferred embodiment of the invention, the support includes a plurality of elongate straps releasably attached to a plurality of complementary fasteners attached to the outer layer of the splint for permitting the straps to encircle and hold the splint in place against the wearer""s hand and wrist while being worn.
According to yet another preferred embodiment of the invention, each of the straps includes a patch of looped material attached to an end of the strap for cooperating with a complementary outer surface of the strap for holding the first and second splints in place against the hand and wrist while being worn.
According to yet another preferred embodiment of the invention, the wrist splint assembly includes a moisture-proof pouch in which the first and second splints are maintained in a flexible condition in a moisture-free environment until the pouch is opened immediately prior to applying one of the splints to the hand and wrist.
According to yet another preferred embodiment of the invention, the outer moisture-proof pouch is formed of a laminated structure having at least one layer of plastic film and at least one layer of aluminum foil bonded to the plastic film.
According to yet another preferred embodiment of the invention, the substrate includes a plurality of overlaid thicknesses of fiberglass.
According to yet another preferred embodiment of the invention, the plurality of thicknesses of fiberglass includes at least five thicknesses and no more than seven thicknesses.
According to yet another preferred embodiment of the invention, a wrist splint product is provided for being custom-fitted to a hand and wrist to be supported. The wrist splint product includes first and second splints. Each of the first and second splints defines a concave side edge extending inwardly toward the longitudinal axis of the splint for permitting enhanced movement of the thumb and associated carpometacarpal joint of the hand. Each splint is formed of a fabric impregnated with a moisture-curable resin that hardens upon curing to form a rigid structure of the fabric that retains a defined shape into which the fabric is molded during curing. The splint product also includes first and second inner storage pouches constructed of a plastic film having moisture-transmission retarding properties, one of the first or second splints being sealed in respective ones of the first and second storage pouches, and a single, outer moisture-proof protective pouch within which the first and second splints and respective first and second inner storage pouches are sealed in the absence of moisture until the first and second splints are to be molded to the body part to be protected.
According to yet another preferred embodiment of the invention, the outer moisture-proof protective pouch is formed of a laminated structure having at least one layer of plastic film and at least one layer of aluminum foil bonded to the plastic film.
According to yet another preferred embodiment of the invention, the plastic film has a thickness of 2 mils and the aluminum foil layer has a thickness of 0.5 mils.
According to yet another preferred embodiment of the invention, the outer moisture-proof protective pouch includes a laminated layer of nylon film.
A preferred embodiment of a method of forming a custom-fitted wrist splint to a hand and wrist includes the steps of providing a first splint for being positioned against and formed to the volar aspect of the hand and wrist, and a second splint for being positioned against and formed to the dorsal aspect of the hand and wrist. Each of the first and second splints includes a multi-layered protective pad positioned in flexible condition in a moisture-impervious storage package and sealed therein against entry of moisture until use. Each of the first and second splints defines a concave side edge extending inwardly toward the longitudinal axis of the splint for permitting ease of movement of the thumb and associated carpometacarpal joint of the hand against which the splint is positioned, and includes an inner cushion layer for being placed on and conformed to the shape of the hand and wrist and an initially flexible intermediate layer overlying the inner cushion layer. The intermediate layer includes a substrate impregnated with a moisture-curable resin that hardens upon curing to form a rigid structure of the substrate that retains a shape into which it is molded during curing for maintaining the flexible inner cushion layer in a conforming shape against the hand and wrist. Each of the first and second splints also includes a flexible outer layer overlying the intermediate layer and attached to the inner cushion layer for enclosing the intermediate layer for forming the inner layer, intermediate layer and outer layer into a single, integrated splint structure. A support is carried by the first and second splints for retaining the first and second splints in position on the hand and wrist during use of said wrist splint. The method also includes the steps of removing a preselected one of the first and second splints from the storage package, exposing the splint to moisture in an amount sufficient to activate the moisture-curable resin, placing the splint against the hand and wrist, and exerting pressure on the splint for a sufficient period of time for the pad to harden, whereby the pad hardens into a rigid, supporting shape custom-fitted to the hand and wrist.